The invention relates to a method for producing a fastening arrangement for the position-correct fastening of a component to a structural part of a motor vehicle.
The invention moreover relates to a fastening arrangement for the position-correct fastening of a component to a structural part of a motor vehicle.
A component being fastened to a structural part of a motor vehicle is for example an instrument, such as a head-up display, without the present invention being restricted to this. A structural part of a motor vehicle to which the component is being fastened is for example a cross beam, part of a cross beam, or a holder fastened to the cross beam, without the present invention being restricted to this. Without limiting the general nature, the method according to the invention and the fastening arrangement according to the invention shall be described by the example of the fastening of a head-up display to a cross beam, part of a cross beam, or a holder fastened to the cross beam.
The cross beam of a motor vehicle is situated between the two A-columns beneath the windscreen and serves as a stabilizing part of the motor vehicle chassis, as well as for the fastening of the steering column, the dashboard, or other components, such as a head-up display.
One problem which occurs in motor vehicle design is that structural parts like the cross beam have manufacturing tolerances after being produced, which are the result of welding processes, for example. Such manufacturing tolerances of a structural part mean that a component being fastened to the structural part cannot be fastened with sufficient precision in position-correct manner to the structural part. In the event that the component being attached is a head-up display, the position-correct fastening of the head-up display to the cross beam is essential. Since the head-up display is an optical instrument by which vehicle parameters such as the instantaneous speed of movement can be projected onto the windscreen and read off by the driver by virtue of reflection from the windscreen, the position-correct placement of the head-up display is especially important. If the orientation and positioning of the head-up display is not correct, it may happen that the vehicle parameters are not projected in the right place or at the right angle onto the windscreen, so that they do not lie in the field of vision of the driver and therefore the driver cannot read off the vehicle parameters, or the vehicle parameters are shown with distortion.
At present, manufacturing inaccuracies during the production of structural parts such as the cross beam are compensated by machining to achieve the required tolerance for the cross beam. However, this has the disadvantage of producing metal chips, and the structural part such as the cross beam is exposed to substantial stresses. Furthermore, such a finish machining of the fabricated structural parts involves additional time and expense.
In document EP 2 420 433 A1 a method and a fastening arrangement for the position-correct fastening of a component to a structural part of a motor vehicle are described, wherein a tolerance compensation element is positioned by means of an adhesive or by means of ultrasound welding relative to the structural part in correct position. The component is then fastened to the tolerance compensation element. In this procedure, manufacturing tolerances at the cross beam are compensated by adjusting the thickness of the adhesive layer or the thickness of the plastic layer produced during the ultrasound welding. Thus, no later machining of the structural part is required with this method. Even so, this known method has the drawback of being cost-intensive. A further drawback is that the method is sensitive to environmental conditions such as temperature and humidity. Moreover, it is necessary for the joints between the tolerance compensation element and the structural part being filled with adhesive or molten plastic to be clean and especially free of grease in order to ensure a secure adhesion of the tolerance compensation element to the structural part. Accordingly, the joints must be cleaned and especially degreased, which in turn involves time and expense. The process stability of this known method therefore cannot be assured without additional expense.
In document EP 1 094 230 A2 a fastening arrangement is described for the fastening of a head-up display in an airplane cockpit, wherein a first part is attached directly to a structural part of the airplane frame by screw fasteners. The first part has a box-like receptacle, in which a second shaft-like part is installed, the box-like receptacle and the shaft representing a kind of ball joint connection. After orienting the second part in the correct position, the remaining space between the shaft and the receptacle is filled with an adhesive, and after the hardening of the adhesive the second part is secured on the first part. This fastening arrangement and the corresponding method for producing this fastening arrangement are likewise labour- and cost intensive.